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This is a true story that I hear from a Venezuelan. There was a match between two softball teams, one from Mexico and another one from Venezuela.

During the match the Venezuelan girls were laughing to tears when the Mexicans were playing defense and kept yelling to each other "cáchala!!" which means "catch it" of course in reference to the ball.

In the same manner the Mexicans couldn't stop laughing when the Venezuelans were playing defense and kept yelling to each other "cógela!!" which means "grab it" also referring to the ball.

Not opposite meanings, but opposite T-V attitudes: "Vos", second person pronoun, is very informal in those regions with 'voseo' (eg. Argentina), and very formal in other regions (Spain). This later form, though, is seldom used (it's rather archaic), and hence there is little chance of confusion. One case I recall: "Jesús, en Vos confío" a traditional spanish christian jaculatory (very short prayer; "Jesus, I put my trust in you") is said verbatim in Argentina, and most people here believe wrongly that the informal "voseo" is used...

PS: This other confusion is not from regional context, rather from the technical, but I experienced it just now, listening to the radio about the "Costa Concordia" shipwreck:
Rumbo : its common meaning is "course" (direction, of a vehicle, a ship...), but in naval/marine context it has a specific technical meaning: a dangerous hole in the hull of the ship. So, if you aboard and happen to hear "¡Tenemos un gran rumbo!" perhaps you think that is good news, when actually it's very bad...

I just noticed the OP was specifically asking for words with opposite meanings in different regions but these all seem to have both opposing meanings no matter the region.
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hippietrailDec 17 '11 at 17:35

1

@hippietrail: true. Luego has the regional characteristic: in Mexico it's used mainly with the first meaning, but in Colombia it's used with the second one.
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Gonzalo MedinaDec 17 '11 at 17:40

BTW, the more common words for those meanings ("pelón" is no very common) are "peludo" (lots of hair) and "pelado" (no hair)... that are quite similar, with no obvious cue of which one is which.
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leonbloyJan 15 '12 at 1:49